Modern ski boots generally perform well, but there remain some unresolved problems in this field. Particular problems relate to the tongue of the boot liner. In general, typical ski boots include some type of relatively hard plastic shell within which is fitted a cushioned, insulated boot liner that includes a padded tongue. When the boot liner is positioned in the shell, the tongue has a high degree of mobility. The tongue is able to move laterally, that is, side to side. As well, the upper portion of the tongue is able to move forward, upon flexing, toward the toe of the shell and releases rearward toward the heel of the shell. Finally, the tongue is able to move vertically up and down. In general, the mobility of the tongue enables a user to more easily insert his foot into the boot, and to remove his foot from the boot. As originally intended, the mobility of the tongue enables a given boot liner to accommodate any of a variety of different foot shapes.
While the mobility of the tongue is beneficial in some respects, it is problematic in others. For example, during normal usage it is common for the boot liner tongue of a ski boot to be pulled forward and up by the flexing nature of the boot. This movement of the tongue can occur every time the boot is flexed and, as a result, one or more of the intended characteristics of the boot, such as boot fit and comfort, ski control, and leverage, may be compromised.
To illustrate with one particular example, if the tongue is not retained in the proper vertical position and lateral position relative to the shin and lower leg of the user, it can be difficult for the user to maintain the correct positioning and orientation of his foot in the boot, since pan or all of the shin and/or lower leg may not be properly restrained by the improperly positioned tongue. Thus, an improperly positioned tongue may allow the lower leg and/or foot of the user to move excessively within the boot liner and/or shell, resulting in inefficient energy transfer to the ski, and reduced control of the ski. Excessive movement of the foot inside the boot can also cause blisters and other discomfort.
Another problem with an improperly positioned tongue, such as a tongue that has moved upward out of position, is that, during normal use of the ski boot, there may be only partial and/or intermittent contact between the shin of the user and the tongue. As a result, the user may experience what is sometimes referred to as shin bang, which occurs when part of the shin moves freely back and forth within the boot liner and/or shell.
One approach to improving maintenance of the tongue position would be to simply tighten one or more of the boot buckles, such as the buckle, or buckles, on the upper cuff portion of the shell. However, while this approach may provide some marginal benefit, overly tight buckles reduce blood circulation, resulting in cold, painful feet.
Simply tightening one or more buckles in an attempt to secure the position of the tongue is insufficient for other reasons as well. For example, tightening of the boot buckles may reduce the extent to which the ankle portion of the boot is able to articulate, thus impairing the mobility of the boot and thereby compromising the ability of the boot to respond to dynamic conditions as the user skis.
In view of problems such as those noted above, it would be useful to provide a ski boot and ski boot liner configured so that undesirable motion of the tongue of the boot liner can be reduced, or eliminated. It would also be useful to be able to constrain vertical and forward motion of the tongue to within acceptable ranges of movement when the ski boot and ski boot liner are used together during normal use conditions.